1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc., which records images on a sheet of paper using an electrophotographic process. The invention particularly relates to an improvement in the installation and removal structure of a developing unit, or an image forming process kit including a developing unit, and a toner cartridge in the image forming apparatus.
2. Discussion of the Background
In an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc., using an electrophotographic process, a latent image formed on a photoconductive member is developed by applying toner from a developing unit onto the photoconductive member. The developed image is then transferred and fixed onto a sheet of paper. It is common that a removable toner cartridge is used to supply toner to the developing unit.
In conventional apparatuses in which a toner cartridge is exchanged while in the developing unit, or an image forming process kit, including the developing unit, is positioned inside the apparatus, or where the toner cartridge is exchanged while the developing unit or the image forming process kit is removed from the apparatus, if the developing unit or the image forming process kit can be inserted or removed without the toner cartridge being mounted thereon, a large amount of toner can be spilled and spread inside the image forming apparatus due to installation or removal shock, or due to turbulent air. As a result, the spread toner adheres to optical devices or a corona discharge wire, and printing quality is deteriorated.
Moreover, in conventional apparatuses in which the toner cartridge is exchanged while the developing unit or the image forming process kit is removed from the apparatus, if the toner cartridge can be removed from the developing unit or the image forming process kit while the developing unit or the image forming process kit remains inside the apparatus, the problem described above can occur because an entrance for supplying toner in the developing unit becomes open inside the apparatus.
Finally, in conventional apparatuses in which the toner cartridge is exchanged while the developing unit, or the image forming process kit including a developing unit, is installed inside the apparatus, if the toner cartridge can be installed and removed while the developing unit or the image forming process kit is removed from the apparatus, and if the cartridge is in fact removed from the developing unit or the image forming process kit, the developing unit or the image forming process kit can be overturned and the toner in the developing unit spilled and spread. Also, when the entrance for supplying toner in the developing unit is opened outside of the apparatus, foreign substances can enter the developing unit and cause serious damage.